The present invention relates to an electronic unit.
In an electronic unit such as an inverter, a power semiconductor device serving as a switching device is operated under the control of a control circuit. In a known electronic unit disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2000-228492, a circuit board having a control circuit thereon is disposed above the power semiconductor device.
FIGS. 9 and 10 show examples of the electronic unit as a background art. Referring to FIG. 9, a circuit board 110 is built into a semiconductor power module 100 which incorporates power semiconductor devices (not shown). The circuit board 110 is disposed in the vicinity of the power semiconductor device. Power terminals 101 and signal terminals 111 are disposed on the upper surface of the semiconductor power module 100. Referring to FIG. 10, a circuit board 210 is provided separately of a semiconductor power module 200. The semiconductor power module 200 and the circuit board 210 are electrically connected via connectors 202 and 211 and electric wires 220. Power terminals 201 are disposed on the upper surface of the semiconductor power module 200.
In the electronic unit of FIG. 9, since the circuit board 10 is affected by heat generated by the power semiconductor device, type of electronic components to be mounted on the circuit board 110 is limited. Therefore, some types of electronic components such as CPU possibly cannot be mounted on the circuit board 110. In addition, the circuit board 110 is affected also by noise generated due to large amount of current flowing through the power semiconductor device. Therefore, a noise shield such as an aluminum plate needs to be provided between the circuit board 110 and the power semiconductor device for protecting circuits and electronic components on the circuit board 110 from the noise. Further, a power capacitor needs to be connected to the power terminals 101 outside the semiconductor power module 100, resulting in enlargement of the size of the electronic unit.
In the electronic unit of FIG. 10, on the other hand, since the semiconductor power module 200 and the circuit board 210 are connected via the connectors 202 and 211 and the electric wires 220, disconnection or contact failure may occur in electric connections. In addition, since the semiconductor power module 200 is provided separately of the circuit board 210, the size of the electronic unit is enlarged. Further, a power capacitor needs to be connected to the power terminals 201 outside the semiconductor power module 200, resulting in enlargement of the size of the electronic unit.
The present invention is directed to providing an electronic unit that allows electronic components thereof to be less affected by heat or noise and offers more reliable electric connection without enlarging the size of the unit.